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A few years back, I put together a lovely engagement ring based around one of the most beautiful tsavorite garnets that I've ever seen. Gorgeous, deep green and internally flawless, it was a pleasure to work with up until the time came to set it. Tsavorites are notoriously brittle, and great care and preparation go into ensuring that the stone will remain in place and in one piece, at least until the customer has picked it up and paid for it. Protecting the stone from future damage is all but impossible in a design like this but, we always do our best under the circumstances.
Well, as fate would have it, the ring was, indeed, whanged against something to such an extent that, not only was the stone chipped, but the cluster setting was distorted beyond all redemption. A rebuild was the only alternative. Fortunately, the customer had ample insurance to cover the costs. Unfortunately, replacing such a gem is all but impossible. They just ain't making them that nice anymore. We did manage to put our hands on quite a beautiful stone that, while it wasn't as nice as the original, was pretty near perfect in its own right.
What you may also notice is that someone else had attempted to fix the ring before it came back to me, the claws being somewhat, ummm... ungainly. Ah, well. At least this presents the opportunity to rebuild the ring and correct some of the shortcomings of the original. Not that there was all that much to complain about, but in this case, I think the connection between the shoulders of the ring and the cluster head was a little tentative, lending a slightly unstable appearance to the whole. In addition, the fact that she was able to crush the setting makes it plain that a somewhat beefier infrastructure is necessary. That being said, we don't want it to appear chunkier, just play around with the engineering.
This being a platinum ring, it allows us to use the properties of the material to simplify the construction and put something together that will last.
The first step in making anything out of platinum is the melting of a Smartie (an M&M, if you're American). Platinum, (in a low-rent shop environment, like mine, anyway) is impossible to cast into a bar, so we start off with a molten lump that is rolled down to a manageable plate, from which we will make the base for the cluster setting.
The Smartie here has cooled to the point that it won't burn the sensor in the camera, but the actual molten platinum can't be viewed without the protection of some heavy-duty welding goggles, as it melts at 1768° Celsius which, in Fahrenheit, is really fucking hot.
The cookie is rolled out to about two millimeters thick and some guidelines scribed in to ensure proper alignment of the stones. These are then laid out in their proper position using a substance called "Setter's Friend". Each stone is picked up with tweezers, touched to the tongue and placed in position. The setter's friend stays wet for long enough that the stones can be moved around until the spacing is absolutely consistent. This initial stage is muy importante, as any compromise now will inevitably lead to larger problems later. The spacing in this case is more or less dictated by the sizes of the existing stones but, since the new garnet is pretty much the same size as the original, this won't present a problem.
Did I mention that setter's friend is spit? Well, it is. Kind of disgusting, really, but always there when you need it. When once the stones are adequately placed, each stone is picked up in turn and its position marked accurately on the plate. Then the stone is replaced in position and the next one in line marked and replaced. The little puddle of gob has left a shadowy mark showing the outline of the table of the stone, so it may be tempting to pick up all the stones and just mark them all at once. This is, in my experience, folly, as tiny inconsistencies will creep in and cause trouble later on.
Once each stone's position is marked, a center point can be established using either a round graver or a center-punch and the holes drilled out. The same kind of obsessive accuracy is called for when drilling the holes, except for the middle hole for the tsavorite, which will be pierced out, so is drilled anywhere convenient within the outline. This is cut out leaving a small ring concentric with each individual diamond hole and cleaned up with the appropriate needle files.
Once the inside is right, the outer shape is cut and cleaned up. This solves one of the mysteries of the cluster setting that confused me when I first encountered them. I wondered how someone could accurately join all those little tubes together without having them all fall apart during some subsequent operation. You live, and, if you're paying attention, you learn.
Adding an inner row of claws would normally be the next step but, in this case, there will be an inner bezel into which the girdles of the diamonds will be undercut, eliminating a fairly ugly step.
Being a belt-and-suspenders kind of guy, I don't trust a single claw in the outer row to secure the diamonds, so I'll add some little stubby ones in between each stone. If I were doing this in white gold, I might use investment soldering to attach all the claws at once, but this would be problematic in platinum, due to the high heat.
Adding the claws one at a time seems like a lot of bother, but it actually goes quite quickly once the technique is perfected. Rather than trying to hold them in place, bending the wire into a tight U allows us to solder them individually and nip them off. Thanks to capillary action and the low heat conductivity of platinum, we don't have to worry about the previous claws falling off. We're using hard platinum solder here, so there's precious little chance of anything getting out of place. Scary stuff.
Once the assembly is cleaned up, it can be treated as a single unit and, because it's platinum, there will be no concern about fireskin, as platinum stubbornly refuses to oxidize, for which we love it.
A tapered collet is formed, into which the garnet just drops. Only a small bearing is necessary for a setting like this, thanks to the rigidity of the assembly and the large number of claws. This allows us to keep each claw very delicate and rest assured that everything will be secure.
This is where it becomes clear how important the initial layout was. If there's any inconsistency in the spacing or sizing of the underbezels, it would be all but impossible to set the stones accurately.
Once the collet drops into place, touching each inner point on the underbezel ring, the upper section can be shaped into nice, delicate claws, leaving just enough material to form the undercuts for the diamonds. This is soldered into the rest of the assembly and, as before, can be treated as one piece.
Next up is to fit the outer claws that form our fancy-ass basket. A groove needs to be cut into the outer edge of each little underbezel to accept a round wire, and then we just have to solder a long piece of appropriately-sized wire into each groove, ensuring that each is firmly snugged into said groove, and perfectly perpendicular to the rest of the cluster head. Nothing to it, right?
Well, with proper preparation, and a cavalier disregard for how much platinum we're using up in this little endeavour, this won't present too much of a problem. The stuff is eminently recyclable, so let's just melt some of the scrap from the previous operations into another, somewhat smaller Smartie, and roll it out to about two millimeters as before. Into this we'll drill (in this case) twelve holes arranged in a slightly smaller oval than previously. These holes need to be just slightly larger in diameter than the wire chosen for the basket wires, so that there's just a little play. Fitting the wires into each hole and sliding our cluster assembly into place under just a tiny amount of tension will allow us to check that each wire fits each groove accurately, as well as ensuring that each is perfectly spaced and aligned. Making sure that the cluster is perfectly level is easily done as well.
When I said easily, I didn't actually mean, you know, easily. The easy part comes from all the preparatory work and attention to detail. As well, there is experience. This is not my first rodeo.
Once all the wires are soldered into place, they can carefully be bent inward to form the basket. If this was a round setting, the best way to do it would be to cut all the wires to the same length and gradually bend them inwards 'til they touch, filing them to a bit of a taper so that they form a solid base. In this case, however, we'll bend them in in opposite pairs, adjusting as we go. There's no formula for this part, so winging it seems the best approach. Turned out rather well, I thought.
A tool that comes in very handy during this ordeal is the cheater file. This is simply a barrette file ground down on its two safe sides to a fine knife-edge. It comes in handy for a multitude of purposes, allowing one to get in tight spaces such as the ones we're dealing with here, correcting the angles as the wires are closed in on one another.
Once the wires have been fitted snugly into place, they can be soldered together and a hole drilled into the center. A post is added and everything cleaned up and what you have here is a bona fide cluster head.
Once again, platinum makes huge sense when putting something this complicated together, thanks to the fact that each step in the operation can be cleaned up and polished without concern for the oxides that plague gold work.
Now it's time for a beer before embarking on the manufacture of the ring upon which we will be placing this beauty.
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